As critical components of cell-mediated immunity, chemokine and chemokine receptors play pivotal roles in leukocyte migration and cell adhesion. A long term objective is to discover and develop small molecular weight drugs that can block the binding of chemokine to its receptor or the downstream signaling pathways, and thereby selectively interrupt an essential step in the inflammation process. Dictyostelium is a simple eukaryote that exhibits well-defined chemotactic responses remarkably similar to that in leukocytes. The genetics and cell biology of Dictyostelium make it an attractive system for reconstituting chemokine receptor-mediated signal transduction component and for developing a high throughput screening assay. The primary goal of this Phase I proposal is to test the feasibility of coupling interleukin-8 receptor (IL8R), a model chemokine receptor, to the signal transduction cascade in Dictyostelium. Specifically, the human IL8R-A and IL8R-B will be expressed on cell surface of Dictyostelium; the mammalian Gai will be co-expressed and the ligand binding activity to IL8R will be determined; and the functional linkage between IL8R and adenylyl cyclase in Dictyostelium will be tested.